Pool swim season in Gardena, CA
Swim season in Gardena without a heater, and with one
An unheated pool in Gardena never reaches 78°F in a normal year. It peaks around 75°F in Aug. The air allows up to 7 swimmable months with a heater (May to Nov).
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Heater options for a Gardena pool, side by side
| Option | Months | Swimmable | Energy/yr | All-in/yr |
|---|---|---|---|---|
| No heater | 0 | no month | $0 | $0 |
| Solar cover only | 3 | Jul to Sep | $0 | $50 |
| Solar panels + cover | 6 | May to Oct | $0 | $283 |
| Heat pump + cover | 7 | May to Nov | $455 | $1,005 |
| Gas heater + cover | 7 | May to Nov | $619 | $1,044 |
For a 450 sq ft pool held at 80°F, at CA prices of 32.6¢/kWh electricity and $22/Mcf gas. All-in spreads the purchase over the equipment's life.
The cheapest way to the full season in Gardena
Solar panels + cover: 6 of 7 possible months for about $283 a year all-in, which works out near $47 for each month it adds.
Before you pay for any heater, buy a solar cover: on its own it adds 3 months here for about $50 a year (why a cover comes first). If you get quotes, ask for a heat pump sized to your pool's surface area; here it beats gas all-in (heat pump or gas).
Weather station: Hawthorne Municipal Airport, 2.5 mi away (NOAA 1991–2020 normals). Water temperature is estimated from air and sunshine, not measured.
Gardena month by month: air, sun and pool water
| Month | Air high | Air avg | Sun kWh/m²/day | Water, unheated | Water, covered | Heat pump $ | Gas $ |
|---|---|---|---|---|---|---|---|
| Jan | 67° | 58° | 3.1 | 58° | 64° | – | – |
| Feb | 67° | 59° | 4.0 | 60° | 66° | – | – |
| Mar | 68° | 60° | 5.2 | 62° | 68° | – | – |
| Apr | 70° | 62° | 6.3 | 65° | 71° | – | – |
| May | 71° | 65° | 6.6 | 67° | 73° | $132 | $179 |
| Jun | 73° | 67° | 6.3 | 69° | 75° | $87 | $122 |
| Jul | 77° | 71° | 6.6 | 73° | 79° | $24 | $34 |
| Aug | 79° | 72° | 6.3 | 75° | 81° | – | – |
| Sep | 79° | 72° | 5.5 | 74° | 80° | – | – |
| Oct | 76° | 68° | 4.3 | 71° | 77° | $52 | $74 |
| Nov | 72° | 63° | 3.4 | 66° | 72° | $160 | $210 |
| Dec | 66° | 58° | 2.8 | 60° | 66° | – | – |
Heating costs most in Nov (about $160 with a heat pump, $210 with gas). Sunshine peaks in Jul at 6.6 kWh/m²/day (NASA satellite data, 47.3 km grid cell). Highlighted months are swimmable with no heater.
How Gardena compares with nearby cities
Gardena ranks 254 of 376 California cities for unheated swim months, and no nearby city gets a longer unheated season.
| City | Distance | Unheated months | Heat pump months | Heat pump $/yr |
|---|---|---|---|---|
| Lawndale, CA | 3 mi | 0 | 7 | $455 |
| Hawthorne, CA | 3 mi | 0 | 7 | $455 |
| Compton, CA | 5 mi | 0 | 7 | $455 |
| Inglewood, CA | 5 mi | 0 | 7 | $455 |
| Carson, CA | 5 mi | 0 | 8 | $862 |
| Torrance, CA | 5 mi | 0 | 6 | $555 |